Fabrication of Ag/ZnO composite nanoflowers for ultrasensitive and recyclable SERS detection toward Rhodamine 6G

Novel Ag/ZnO composite nanoflowers (CNFs) had been designed as a surface-enhanced Raman scattering (SERS) substrate for organic molecule detection. Flower-like ZnO architecture was firstly synthesized by a low-temperature precipitation method, and subsequently Ag nanoparticles were decorated on ZnO nanoflowers through a photochemical reaction. The optimal Ag component was investigated by changing the photo-reduction time of Ag + in the ZnO precursor solution. It is found that the Ag nanoparticles with suitable size and crystallinity are significantly related to the light absorption and Raman signals for Ag/ZnO substrate. For Rhodamine 6G (R6G) as probe molecules, the optimal Ag/ZnO-40 min CNFs achieve a low detection limit of 1.0 × 10 −12  M and a high enhanced factor (EF) of 1.74 × 10 6 . Due to its excellent photocatalytic activity, the Ag/ZnO active substrate effectively degrades R6G molecules adsorbed on the surface, displaying an excellent self-cleaning property and stable recyclability. Such a superior SERS performance can be attributed to the synergy effect of two components (Ag nanoparticles and ZnO nanoflowers) such as its unique architecture, charge transfer and high-density hot spots.